# Define here the models for your spider middleware
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/spider-middleware.html

import json
from time import sleep
from scrapy import signals
from itemadapter import is_item, ItemAdapter
from scrapy.http import HtmlResponse
from selenium import webdriver
from selenium.webdriver.chrome.options import Options

# useful for handling different item types with a single interface
from itemadapter import is_item, ItemAdapter


class LagouSpiderMiddleware:
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, or item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Request or item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class LagouDownloaderMiddleware:
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    #要用selenium在这里改
    #settings中的DOWNLOADER_MIDDLEWARES需要打开并设置
    def process_request(self, request, spider):
        #self.driver在最后面的spider_opened(self, spider):中定义，框架一起动就会调用这个函数
        #在spider文件中
        driver = self.driver
        if request.url.endswith("******"):
            next = driver.find_element_by_xpath('//span[@action="next"]')#获取下一页的span
            next.click()#进行点击
        else:
            driver.get(request.url)
        sleep(2)
        content = driver.page_source
        # driver.close()
        response = HtmlResponse(url=request.url, body=content.encode("utf-8"), encoding="utf-8")
        return response

        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    #启动时会先运行这个方法
    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)

        #设置为无界面浏览器
        #options = Options()
        #options.add_argument("--headless")
        #driver = webdriver.Chrome(options=options)

        driver = webdriver.Chrome()
        driver.get('https://www.lagou.com/')

        #使用储存好的cookie进行登陆
        driver.delete_all_cookies()
        with open('lagou_cookies.txt', 'r', encoding='utf-8') as file:
            cookies_str = file.read()
        cookies = json.loads(cookies_str)

        for cookie in cookies:
            driver.add_cookie(cookie)

        driver.refresh()
        self.driver = driver
